The present invention relates generally to the field of rail locomotives, and more particularly to methods and apparatus for controlling a turbo-charged diesel locomotive engine.
Excessively high pressure in an operating cylinder of an internal combustion engine may cause damage to the engine pistons, cylinder heads, and other components. Peak firing pressure (PFP) is affected by the combustion process and the conditions of the incoming combustion air. In addition, the operation of a turbo-charger increases peak firing pressure by increasing the temperature and pressure of the incoming air.
Locomotives encounter a variety of operational conditions ranging from extreme cold at sea level to hot temperatures at high altitudes. These conditions may induce various engine parameters to exceed designed engine limits, for example, peak firing pressure (PFP), turbocharger speed (TS), and preturbine temperature (PTT). More specifically, the parameters are more susceptible to being exceeded when the engine is running at full load at extreme ambient temperature and/or altitude conditions.
There is also a continued demand for improved performance of locomotive engines, in terms of fuel economy, component loading, power output and reduced emissions. To facilitate optimized engine performance, conditions of combustion within the internal combustion engine should be controlled. However, engine designs are limited because of the extremes of environmental conditions under which a locomotive must operate. For example, cylinder PFP may become too high when an engine is operating during cold days and when the inlet air temperature is low, thus generating excessive stress on engine components. Alternatively, cylinder exhaust temperatures may become too high when the engine is operated during hot days and when the inlet air temperature is very high, thus causing turbocharger damage due to overheating and overspeed.
To facilitate controlling PFP, TS and PTT the engine may be operated with a power derate such that the engine is operated at lower than rated horsepower. However, derated engine operation is undesirable because it unnecessarily limits the operational capability of the locomotive.
In one aspect, a method of operating a turbo-charged diesel locomotive engine to facilitate controlling pressure in an engine cylinder is described. The method includes determining an allowable peak firing pressure for the turbo-charged diesel engine, determining an actual peak firing pressure, and comparing the allowable peak firing pressure to actual peak firing pressure to control operation of the turbocharger for controlling peak firing pressure.
In another aspect, a method of operating a turbo-charged diesel locomotive engine to facilitate preventing damage from turbocharger failure is described. The method includes determining an allowable turbine speed for the turbocharger, determining an actual turbine speed, and comparing the allowable turbine speed to actual turbine speed to control operation of the turbocharger for controlling turbocharger speed.
In yet another aspect, a method of operating a turbo-charged diesel locomotive engine is described. The engine includes a turbo-charger for providing compressed air to an intake manifold of the engine, a motor-generator coupled to the turbocharger shaft, and an electronic controller receiving inputs from engine components. The method includes determining at least one of an allowable peak firing pressure for an engine cylinder, an allowable turbine speed for the turbocharger, an allowable preturbine temperature, an actual peak firing pressure as a function of at least one of an intake manifold air pressure, a manifold air temperature, and a timing of fuel injection into the cylinder, an actual turbine speed, and an actual preturbine temperature, using the electronic controller to compare at least one of the allowable peak firing pressure to the actual peak firing pressure, the allowable turbine speed to actual turbine speed, and the allowable preturbine temperature to the actual preturbine temperature, using the electronic controller to control the motor-generator, and operating the motor-generator to at least one of increase power input to the turbocharger shaft to increase the turbocharger rotational speed, decrease power input to the turbocharger shaft to decrease the turbocharger rotational speed, and maintain turbocharger rotational speed.
In still another aspect, a locomotive power unit is described. The power unit includes a diesel engine including an intake manifold for receiving compressed air, an exhaust manifold for removing exhaust, and an electronic fuel controller receiving inputs from engine components, a turbo-charger including a turbine section connected to the exhaust manifold and a compressor section including an outlet connected to the intake manifold, the turbo-charger operable to provide compressed air to the intake manifold at an intake manifold air pressure, a motor-generator coupled to the turbocharger and operable to at least one of increase turbocharger rotational speed, decrease turbocharger rotational speed, and maintain turbocharger rotational speed; and a controller including a first input corresponding intake manifold air pressure and a second input corresponding to fuel injection timing for the engine and including as an output a motor-generator configuration signal, the output being responsive to the first input and the second input; and the motor generator being responsive to motor-generator configuration signal.